1. Field of the Invention
The present invention relates to room temperature controllers, and more particularly, to room temperature controllers including means positioned within a room for detecting from a distance the presence of an occupant within the room.
2. Description of the Prior Art
The prior art includes a number of different types of devices for detecting the presence of a person within a predetermined area. U.S. Pat. No. 4,024,413 (Olita) discloses a sound activated switch which illuminates an electric light in response to sounds generated by keys. U.S. Pat. No. 3,573,817 (Akers) discloses a multiple-sensor monitoring system which includes an audio sensor for detecting the presences of sounds within the area being monitored.
U.S. Pat. Nos. 2,655,645 (Bagno) and 3,597,754 (Lerner) disclose ultrasonic motion detector systems designed to detect a moving object within a monitored area.
The prior art also discloses numerous types of energy control systems for room heating and cooling units which modify the ambient room temperature when an occupant is not within a particular room. U.S. Pat. No. 4,060,123 (Hoffman) discloses a key actuated device of this type which permits the thermostat of a room air conditioning unit to operate normally when a key is inserted into the device. When an occupant is not present within the room, an unoccupied room status is indicated and the room air temperature is permitted to either rise or fall to a predetermined heating and cooling limit to reduce energy consumption by the room air conditioning unit. A related invention of this type is disclosed in U.S. Pat. No. 3,934,797 (Perlmutter). The Perlmutter patent discloses a dual range thermostat. One of the temperature ranges of the thermostat corresponds to an unoccupied temperature setting while the other range corresponds to an occupied temperature setting. A clock which can be preset swithes the thermostat between the occupied and the unoccupied temperature ranges.
The prior art discloses numerous different types of thermostatic control devices which control the operation of an air conditioning unit in response to a number of different input parameters. U.S. Pat. No. 4,020,897 (Enter) discloses an automatic interior environment control system which senses the intensity of solar radiation, daily solar radiation accumulation, nocturnal temperature modification, and other parameters to control the operation of an environmental control system. U.S. Pat. No. 3,246,839 (Steghart) discloses a device for controlling a central heating system which senses numerous parameters such as wind velocity, outside temperature and solar radiation intensity. U.S. Pat. No. 4,024,725 (Uchida) discloses a control system for an air conditioner which senses parameters such as room temperature, room air flow velocity, relative humidity and radiation temperature. U.S. Pat. No. 4,040,565 (Thistiansen) discloses a control unit for thermal conditioning systems and includes outside and inside temperature measuring devices and an analog computer which determines the required amount of "on time" for the air conditioning system.
U.S. Pat. No. 3,050,601 (Bohm) discloses a temperature control system having a mechanically driven, time variable cycling thermostat. U.S. Pat. No. 3,102,689 (Ditto) discloses a temperature controller which includes both an on-off control and a time-proportioning control. U.S. Pat. No. 4,020,358 (Wylend) discloses a device for controlling the supply of power to an electrical load. This device includes a temperature sensor.